An interventional study of Polarided training intensity distribution and Threshold Training Intensity Distribution in Endurance Exercise, Exercise Physiology and Running Performance, sponsored by Universidad Rey Juan Carlos. Completed at 1 site in Spain. Open to participants aged 18 Years to 60 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-05-11.
Sponsored by Universidad Rey Juan Carlos · Not applicable, Interventional, and Other
This study aims to compare the effects of three different training intensity distribution (TID) models-polarized, threshold, and pyramidal-on physiological and performance adaptations in recreational distance runners. Twenty-four participants will be assigned to one of the three training interventions and will complete an 8-week structured running program based on the respective TID approach.
The primary objective is to determine whether different TID models elicit distinct changes in key physiological markers and endurance performance. The study seeks to answer whether a specific intensity distribution strategy provides superior adaptations in recreational runners when training is prescribed over a controlled intervention period.
This study adopts a parallel-group experimental design to compare the effects of three training intensity distribution (TID) models-polarized, threshold, and pyramidal-on physiological and performance adaptations in recreational distance runners.
Eligible participants are required to be recreational runners with a minimum training frequency of four sessions per week. Following enrollment, all participants complete a one-week pre-intervention phase dedicated to baseline assessments and familiarization with testing procedures.
During this phase, participants will performe a comprehensive physiological evaluation to determine key endurance-related variables. These include ventilatory thresholds (e.g., VT1 and VT2), running economy, and maximal oxygen uptake (VO₂max), assessed through an incremental exercise test under standardized laboratory conditions. In addition, participants perform a 5-km time trial on a standardized course or controlled conditions to assess endurance performance.
Based on the physiological assessment, individual training intensities are prescribed using a five-zone intensity model derived from ventilatory thresholds and maximal aerobic capacity. This approach allows for precise classification of training load and ensures consistency in the application of the three TID models across participants.
Following baseline testing, participants are allocated to one of the three intervention groups (polarized, threshold, or pyramidal) and complete an 8-week structured endurance training program. Each training model differs in the relative distribution of time spent across the five intensity zones, while overall training frequency and general structure are maintained comparable between groups.
Training sessions are monitored using participants' GPS-enabled sport watches, which record variables such as duration, distance, pace, and heart rate. These data are used to quantify training load and verify adherence to the prescribed intensity distribution. Participants are instructed to follow the assigned training program and upload their training data regularly for supervision and compliance tracking.
At the end of the 8-week intervention, all baseline assessments are repeated under the same conditions. This includes the physiological testing to reassess ventilatory thresholds, running economy, and VO₂max, as well as the 5-km time trial to evaluate changes in endurance performance.
The primary aim of the study is to examine whether different TID models induce distinct adaptations in physiological determinants and performance outcomes when applied in a controlled, prospective training intervention in recreational runners.
Universidad Rey Juan Carlos is the lead sponsor of 111 studies on the registry; 22 are open to participants now.
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Exclusion Criteria:
Participants assigned to the polarized training group perform an 8-week structured endurance training program characterized by a high proportion of low-intensity exercise and a smaller proportion of high-intensity exercise, with minimal time spent at moderate intensities. Training intensity is prescribed using an individualized five-zone model based on baseline physiological assessments. The majority of training is performed in the lowest intensity zones (Zones 1-2), while high-intensity sessions are conducted in the highest zones (Zones 4-5). Training load and adherence are monitored using GPS-enabled sport watches.
Other: Polarided training intensity distribution
Participants assigned to the threshold training group complete an 8-week structured endurance training program emphasizing a greater proportion of training at moderate-to-high intensities, particularly around the second ventilatory threshold. Training intensity is prescribed using an individualized five-zone model derived from baseline physiological assessments. A substantial portion of training is performed in intermediate zones (Zones 3-4), with comparatively less time spent at low (Zones 1-2) and high intensities (Zone 5). Training sessions are monitored via GPS-enabled sport watches to ensure adherence.
Other: Threshold Training Intensity Distribution
Participants assigned to the pyramidal training group perform an 8-week structured endurance training program characterized by a progressive decrease in training volume from low to high intensities. Training intensity is prescribed using an individualized five-zone model based on baseline physiological assessments. Most training is accumulated in low-intensity zones (Zones 1-2), with moderate amounts in intermediate zones (Zone 3) and smaller proportions at higher intensities (Zones 4-5), forming a pyramidal distribution. Training load and compliance are monitored using GPS-enabled sport watches.
Other: Pyramidal Training Intensity Distribution
This intervention consists of an endurance training program based on a polarized intensity distribution model. Training intensity is prescribed using an individualized five-zone system derived from physiological assessments (e.g., ventilatory thresholds and maximal oxygen uptake). The model is characterized by a high proportion of training performed at low intensities (Zones 1-2) and a smaller but meaningful proportion at high intensities (Zones 4-5), with minimal time accumulated at moderate intensities (Zone 3). This distribution aims to maximize adaptations by combining extensive low-intensity volume with targeted high-intensity stimuli.
Also known as: POL
Participants assigned to the threshold training group complete an 8-week structured endurance training program emphasizing a greater proportion of training at moderate-to-high intensities, particularly around the second ventilatory threshold. Training intensity is prescribed using an individualized five-zone model derived from baseline physiological assessments. A substantial portion of training is performed in intermediate zones (Zones 3-4), with comparatively less time spent at low (Zones 1-2) and high intensities (Zone 5). Training sessions are monitored via GPS-enabled sport watches to ensure adherence.
Also known as: THR
Participants assigned to the pyramidal training group perform an 8-week structured endurance training program characterized by a progressive decrease in training volume from low to high intensities. Training intensity is prescribed using an individualized five-zone model based on baseline physiological assessments. Most training is accumulated in low-intensity zones (Zones 1-2), with moderate amounts in intermediate zones (Zone 3) and smaller proportions at higher intensities (Zones 4-5), forming a pyramidal distribution. Training load and compliance are monitored using GPS-enabled sport watches.
Also known as: Pyr
Maximal Oxygen Uptake (VO₂max)
Assessment of changes in maximal oxygen uptake (VO₂max) obtained during an incremental exercise test. VO₂max is used as a measure of maximal aerobic capacity and cardiorespiratory fitness.
Time frame: Baseline to 8 weeks
Ventilatory Thresholds and Associated Running Speeds
Assessment of changes in the first and second ventilatory thresholds (VT1 and VT2) and their corresponding running speeds, determined during an incremental exercise test. These variables reflect submaximal endurance capacity and physiological determinants of performance and their changes after intervention.
Time frame: Baseline to 8 weeks
Running Economy
Assessment of changes in running economy, defined as the oxygen cost of running at a standardized submaximal speed during laboratory testing. This measure reflects the efficiency of movement during endurance exercise.
Time frame: Baseline to 8 weeks
Changes in 5-km time trial performance
Assessment of changes in endurance performance measured as completion time in a 5-km time trial conducted under standardized conditions. Pre- to post-intervention differences are used to evaluate the effect of the training interventions on real-world running performance.
Time frame: Baseline to 8 weeks
Plan to share: No
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